A dual-function chemical probe for detecting erasers of lysine lipoylation

Lysine lipoylation plays vital roles in cell metabolism and redox processes.For example,removal of lipoylation will decrease pyruvate dehydrogenase activity and affect the citric acid cycle.Despite the important functions of lysine lipoylation,the mechanisms for the addition and removal of this modification remain largely unexplored.Very few useful chemical tools are available to study the interactions of lysine lipoylation with its regulatory delipoylation proteins.For example,immunoaffinity purification-mass spectrometry is one of such tools,which highly relies on antibody efficiency and purification techniques.Single-step activity based fluorogenic probes developed by our groups and others is also an efficient method to study the deacylation activity.Affinitybased labeling probe using photo-cross-linker is a powerful platform to study the transient and dynamic interactions of peptide ligands with the interacting proteins.Herein,we have designed and synthesized a dual-function probe KTLlip for studying enzymatic delipoylation(eraser)activity and interaction of lysine lipoylation with the eraser at the same time.We show that KTLlip can be used as a useful tool to detect delipoylation as demonstrated by its ability to fluorescently label the eraser activity of recombinant Sirt2.We envision that the probe will help delineate the roles of delipoylation enzyme in biology.     

A simple method for labeling lipids in the bile lipoprotein

A simple method is proposed for the specific radioactive labeling of phosphatidylcholines and cholesterol in the bile lipoprotein complex. It can be used for human and animal bile samples and results in labeling with the desired specific radioactivity and position. Experiments which determined the intermicellar concentration of lipid constituents suggested that incorporation of radioactive lipids could occur through small dialyzable structures termed mixed premicelles in therm odynamic equilibrium with the bile lipoprotein complex.     

A synthesis method for chemical plant operating procedures

A strategy is proposed for the systematic synthesis of operating procedures for chemical processing facilities. This strategy is based on artificial intelligence techniques, most importantly planning with constraints. Introduced in this paper is the technique of symbolic functional modelling, which has particular application in planning operating procedures for processes with recycle streams. Also introduced is the concept of stationary states, which are used as targets during procedure planning and real time operations, along with a decomposition strategy for the discovery of stationary states. Some of this methodology is implemented in a computer program called POPS (Prototype Operating Procedure Synthesis program). The application of POPS to a hydrocarbon chlorination process startup is illustrated.     

A method for modelling of complex chemical kinetics

A generalized approach to computation of chemical kinetics is given. In the method presented, the stoichiometry of the reactions and the form of reaction rate expressions are input in matrix form. Nonintegral stoichiometric coefficients are possible and the reaction orders are not limited to being only a subset of the former. With examples of three fundamental reactor types (homogeneous batch, tubular plug-flow and continuous stirred-tank reactor) it is shown that it is possible to formulate in a simple and straightforward way mathematical models of chemical reactors which are general with respect to complex reaction kinetics. The general simulation program, based on this method, was successfully used for the trial-and-error identification of the hypothetical kinetic structure of a biochemical process.     

Parylene-C thin films deposited on polymer substrates using a modified chemical vapor condensation method

The properties of parylene-C thin films deposited on polymer substrates using a modified chemical vapor condensation technique were investigated. The configuration of the polymerization chamber was altered from horizontal to vertical and designed with a circular symmetry in the z-direction to improve the deposition rate. The growth rate of the thin films was improved 2–5 times in a vertical configuration compared to a horizontal configuration. Potential factors responsible for such an improvement include the effect of coincidence between the flow direction of the gases and the direction of the convection in the reaction tube due to buoyancy. The synthesized films have a high transparency (>90%) in the visible region, a smooth surface morphology (Rs<5.0 nm), and amorphous phase structures with the presence of some crystalline domains.     

A simple chemical method for stabilization of rice bran

A new simple chemical method for stabilization of rice bran is described. The process, based on the principle that lipase activity will be low at low pH, uses hydrochloric acid at 40 l/ton of bran for lowering the pH of rice bran from 6.9–6.0 to 4.0. The acid can be applied easily by sprinkling or spraying. The operation on small lots can be done by hand mixing of bran, but it is more efficient and effective if mechanical mixing, like a rotary or a trough mixer, is used. This simple method, which takes less than 4 min for a batch of 15 kg, will be useful for stabilization of rice bran in rice mills or where steam or electricity is unavailable. The process is being evaluated in commercial trials.     

Differential scaling: A method for chemical reactor modelling

A mathematical method is presented for the design of partial, distorted models for which specified quantities may be held invariant on change of scale. The method is applied to tabular reactors for homogeneous, gas-phase reactions and in particular to a prototype reactor designed to produce ketene from acetone. The results for this particular problem are compared with those from modeling methods based on the principle of similarity.     

A lysine sensor for process control

A lysine sensor for process control of lysine fermentation was developed based on a Clark-type electrode in combination with L -lysine-α-oxidase. The enzyme, isolated from Trichoderma viride, was immobilized between a cellulose and a polypropylene foil using a polyurethane resin. Lysine determinations were carried out in a flow-through system as anodic measurements when H₂O₂ was measured and as chathodic measurements when the consumption of O₂ was followed. The sensitivity of the sensor toward other amino acids was determined.     

A novel method for the fabrication of freestanding PZT features on substrates

A simple and cheap micromoulding fabrication route was developed to prepare freestanding piezo active features. Dimensions as small as 200 μm by 200 μm and 40 μm high were successfully fabricated via a replication technique. The lead zirconate titanate features were thoroughly characterized using SEM, EDX and XRD analysis. The properties of the features were influenced by several factors like the type of substrate, sintering temperature and sintering atmosphere. Features prepared on alumina substrates and sintered in lead atmosphere displayed a structure with reproducible dimensions. Next to that they were low in porosity and had a comparable composition with respect to the starting powder. The remanent polarization of the lead zirconate film was 12.3 μC/cm² and the coercive field was 8.7 kV/cm.     

A novel electrochemical method for visual detection of surface inclusions in metallic substrates

An electrochemical method is presented for fast and non-destructive detection of surface inclusions in metals and alloys. Using electrode modification techniques, the sample surface is coated with a dark layer; the non-conductive inclusions remain uncoated and thus appear bright and highly visible. The new technique is demonstrated on different alloys with simulated and real inclusions.     

A global optimization method for model selection in chemical reactions networks

Model inference is a challenging problem in the analysis of chemical reactions networks. In order to empirically test which, out of a catalogue of proposed kinetic models, is governing a network of chemical reactions, the user can compare the empirical data obtained in one experiment against the theoretical values suggested by the models under consideration. It is thus fundamental to make an adequate choice of the decision variables (e.g. initial concentrations of the different species in the tank) in order to have maximal separation between sets of concentrations provided by the theoretical models, making then easier to identify which of the theoretical models yields data closest to those obtained empirically under identical conditions.In this paper we illustrate how global optimization techniques can be successfully used to address the problem of model separation, as a basis for model selection. Some examples illustrate the usefulness of our approach.     

基于约翰逊转换的鲁棒化工过程监控方法

化工厂中一个小故障可能导致大事故,从而造成生命财产损失和环境破坏。为了防止小故障演变成大事故,化学工业需要有效的过程监控来及时检测故障和诊断故障原因。传统化工过程监控方法主元分析法(Principal Component Analysis, PCA)假设数据服从高斯分布,实践中有时并不满足该条件。此外,其使用方差、协方差捕捉数据非线性变化时,鲁棒性较差。本工作提出一种改进的主元分析法—基于约翰逊转换的鲁棒过程监控方法。首先引入约翰逊正态转换(Johnson Transformation)使过程数据服从高斯分布;其次使用鲁棒性强的斯皮尔曼相关系数(Spearman Correlation Coefficient)矩阵代替传统主元分析法的协方差矩阵提取特征向量,构造特征空间;最后将过程数据投影到特征空间,使用T2和SPE统计量实施过程监控。将此方法应用于TE过程故障案例,并与PCA和核主元分析法(Kernel Principal Component Analysis, KPCA)对比,验证了此方法的有效性。     

基于元素分析的生物质化学组成快速分析方法

生物质中纤维素、半纤维素和木质素含量的准确分析对于生物质的利用很重要。基于元素分析和集总模型化合物,提出了一种快速、简便分析生物质中主要化学成分含量的方法,并将这种方法用于分析九种不同类型生物质中主要成分的含量。结果发现九种生物质主要成分含量的计算结果与化学方法得到的结果符合良好,分析误差在10%以内。     

绝缘衬底上化学气相沉积法生长石墨烯材料

利用化学气相沉积法,在Si衬底、蓝宝石衬底和SiC衬底上生长石墨烯材料,研究石墨烯的表面形貌、缺陷、晶体质量和电学特性。原子力显微镜、光学显微镜和拉曼光谱测试表明,Si₃N₄覆盖层可以有效抑制3C-SiC缓冲层的形成;低温生长有利于保持材料表面的平整度,高温生长有利于提高材料的晶体质量。5.08 cm蓝宝石衬底上石墨烯材料,室温下非接触Hall测试迁移超过1000 cm²·V^-1·s^-1,方块电阻不均匀性为2.6%。相对于Si衬底和蓝宝石衬底,SiC衬底上生长石墨烯材料的表面形态学更好,缺陷更低,晶体质量和电学特性更好,迁移率最高为4900 cm²·V^-1·s^-1。     

A dynamic-inner LSTM prediction method for key alarm variables forecasting in chemical process

With the increase in the complexity of industrial system, simply detecting and diagnosing a fault may be insufficient in some cases, and prognosing the fault ahead of time could have a certain necessity. Accurate prediction of key alarm variables in chemical process can indicate the possible change to reduce the probability of abnormal conditions. According to the characteristics of chemical process data, this work proposed a key alarm variables prediction model in chemical process based on dyna...     

High-throughput construction method for expression vector of peptides for NMR study suited for isotopic labeling

Fusion protein constructs for labeled peptides were generated with the 114 amino acid thioredoxin (TRX), coupled with the incorporation of a histidine tag for affinity purification. Two tandem AhdI sites were designed in the multiple cloning site of the fusion vector according to our novel unidirectional TA cloning methodology named PRESAT-vector, allowing one-step background-free cloning of DNA fragments. Constructs were designed to incorporate the four residue sequence Ile-Asp-Gly-Arg to generate pure peptides following Factor Xa cleavage of the fusion protein. The system is efficient and cost-effective for isotopic labeling of peptides for heteronuclear NMR studies. Seven peptides of varying length, including pituitary adenylate cyclase activating polypeptide (PACAP), vasoactive intestinal peptide (VIP) and ubiquitin interacting motif (UIM), were expressed using this TRX fusion system to give soluble fusion protein constructs in all cases. Three alternative methods for the preparation of DNA fragments were applied depending on the length of the peptides, such as polymerase chain reaction, chemical synthesis or a 'semi-synthetic method', which is a combination of chemical synthesis and enzymatic extension. The ability easily to construct, express and purify recombinant peptides in a high-throughput manner will be of enormous benefit in areas of biomedical research and drug discovery.